The present invention relates to a vehicle having a running control device for regulating automatically vehicle-to-vehicle distance by controlling the vehicle""s engine, transmission, brakes, motor, generator or otherwise.
A vehicle-to-vehicle distance control device used to follow automatically a preceding vehicle, is disclosed in Japanese patent prepublication No. 137561/1995. The disclosed vehicle-to-vehicle distance control device determines the distance between a preceding vehicle and an xe2x80x9cown vehiclexe2x80x9d (that is, the controlled vehicle having the control device), and adjusts the vehicle-to-vehicle distance by controlling a vehicle throttle when the latter is smaller than a first preset vehicle-to-vehicle distance. Further, when the vehicle-to-vehicle distance is larger than a second preset vehicle-to-vehicle distance, the vehicle-to-vehicle distance is adjusted by controlling the throttle. When the vehicle-to-vehicle distance is between the first vehicle-to-vehicle distance and the second vehicle-to-vehicle distance, an adjustable speed control is carried out based on the amount of variation in the vehicle-to-vehicle distance. The stronger brake fluid pressure is at the time when the vehicle-to-vehicle distance is smaller than the first vehicle-to-vehicle distance, the shorter the vehicle-to-vehicle distance becomes, and the longer, the weaker. At the time of the second vehicle-to-vehicle distance it is set to zero. Also, setting is made so that the larger throttle opening when the vehicle-to-vehicle distance is longer than the first vehicle-to-vehicle distance is, the longer the vehicle-to-vehicle distance becomes.
In a corresponding way, the vehicle-to-vehicle distance which a driver provides differs when the preceding vehicle is stopping and when it is running. A vehicle-to-vehicle distance control device which automates starting and stopping should control the vehicle in such a manner as to provide a vehicle-to-vehicle distance that gives a vehicle occupant a feeling of safety when the preceding vehicle is stopping, and when it is running. In the prior art, braking force is determined on the basis of the vehicle-to-vehicle distance and the speed of an own vehicle, within the limit below the first vehicle-to-vehicle distance; therefore, although the safety of an occupant is ensured, the vehicle-to-vehicle distance at the time of stopping is uncertain and it is not possible to give an occupant a sufficient feeling of safety. In order to give the occupant the feeling of safety, it is necessary to cause his vehicle to stop smoothly, with an appropriate vehicle-to-vehicle distance every time the preceding vehicle stops.
An object of this invention is to provide a running control device which gives an occupant the feeling safety, and causes a vehicle to stop with an appropriate vehicle-to-vehicle distance.